<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title></title>
</head>

<body>
    <nav>
        <a href="#page-1">1</a>
        <a href="#page-2">2</a>
        <a href="#page-3">3</a>
        <a href="#page-4">4</a>
        <a href="#page-5">5</a>
    </nav>
    <div class="box">
        <div id="page-1">1</div>
        <div id="page-2">2</div>
        <div id="page-3">3</div>
        <div id="page-4">4</div>
        <div id="page-5">5</div>
    </div>
    <style>
        body,
        html {
            scroll-behavior: smooth;
        }

        nav {
            width: 790px;
            padding: 5px;
            border: 1px solid black;
        }

        a {
            font-size: 2em;
            text-decoration: none;
        }

        .box {
            width: 800px;
        }

        .box div {
            height: 500px;
            border: 1px solid #000000;
            font-size: 5em;
        }
    </style>
</body>

</html>